Preparation And High Temperature Tribological Properties Of Non-textured And Textured Si-doping Diamond-like Carbon Films

Diamond like carbon（DLC）thin films are solid lubricating films with excellent properties such as high hardness,low friction,and low wear.They have been widely used in aerospace,mechanical,biomedical,and other fields.However,under high temperature conditions（>400℃）,the decrease in thermal stability of DLC films and the formation of wear debris at the friction interface can worsen the tribological properties of DLC films,thereby limiting their application in high temperature environments.Based on the fact that Si doping can improve the thermal stability of DLC（Si-DLC）thin films,and surface texturing can capture debris generated during friction.This paper proposes a new idea of improving the high-temperature tribological properties of DLC thin films by coupling Si doping and texturing.Through magnetron sputtering technology and using a new grid covering technology,non textured and textured Si-DLC thin films have been prepared,The effects of Si content and texture parameters（area ratio,width,depth）on the structure,mechanical properties,and high-temperature tribological properties of Si-DLC films were systematically studied.The main research results are as follows:（1）Si-DLC films with different Si contents were prepared,and the structure,mechanical and high-temperature tribological properties of Si-DLC films were studied.The research shows that when the Si C target power is 0、100、200、300W,the Si content of the Si-DLC film is 0,0.93,2.91,5.04 at.%,the corresponding I_D/I_Gare 2.23,2.21,2.14,2.06,respectively,the hardness is 15.2,16.3,17.5,17.2 GPa,respectively,and the internal stress is-2.36,-2.25,-2.01,and-1.85 GPa,respectively.The tribological properties of DLC films without Si doping at 450 were tested and analyzed.The results showed that the DLC films with Si content of 0.93,2.91,5.04 at.%failed rapidly,and the average friction coefficients were 0.028,0.033,0.090,and the wear rates were 0.35×10^-6、0.07×10^-6、2.33×10^-6mm³/N×m。The friction test at 500℃showed that the heat resistance time of Si-DLC thin films increased with the increase of Si content,and only the Si-DLC thin films with Si content of 5.04%did not fail in the test experiment.The analysis shows that with the increase of Si content,the sp³-C content of Si-DLC films increases,resulting in an increase in film hardness and thermal stability.However,high Si doped DLC thin films have more abrasive debris formed at their friction interfaces,resulting in large and violent fluctuations in their friction coefficients and high wear rates.（2）The surface of 5.04%Si content Si DLC thin films was textured by grid covering texture technology,and their structure,mechanical and high-temperature tribological properties were systematically studied.The research shows that the friction coefficient curves of Si-DLC films with texture width and depth of 350μm and 170 nm are relatively stable,with friction coefficient and wear rate of 0.043 and 3.4×10^-7mm³/N×m,respectively.The analysis shows that the texture parameters have a significant impact on the high-temperature tribological properties of Si-DLC films.Firstly,if the texture area ratio is too small,the storage rate of wear debris is limited.If the texture area ratio is too large,the dual ball is prone to sink into pits and the friction coefficient increases.When the textured area ratio is 51%,Si-DLC thin films have excellent tribological properties.Secondly,when the texture width of Si-DLC thin films increases,their ability to capture debris increases.The tribological properties of thin films with a texture width of 350μm are relatively optimal.In addition,when the texture depth is too small,the wear debris storage rate is limited,exacerbating abrasive wear.When the texture depth is too large,the texture edge is prone to fracture,increasing the wear rate.The tribological properties of Si-DLC films with a texture depth of 170 nm are the best.